JP4335080B2 - Wheel support device - Google Patents

Description

  The present invention relates to a wheel support device for instructing a vehicle suspension system to freely rotate a wheel.

In a wheel support device for supporting a non-drive wheel such as a front wheel in a rear wheel drive type vehicle, two rolling bearings are mounted on an axle (knuckle spindle) provided on a steering knuckle and are supported rotatably by the rolling bearing. A flange is provided on an outer diameter surface of the axle hub, and a brake drum of a brake device and a wheel disc of a wheel are attached by a stud bolt provided on the flange and a nut engaged with the stud bolt.
Further, a back plate is attached to a flange provided in the steering knuckle, and a braking mechanism for applying a braking force to the brake drum is supported by the back plate.
In the wheel support device as described above, a tapered roller bearing having a large load capacity and high rigidity is used as a rolling bearing that rotatably supports an axle hub. The tapered roller bearing is lubricated by grease filled between the axle and the axle hub.

Bearings used in wheel support devices are subject to harsh usage conditions such as high speed and high load, and especially because the bearing ring collar slides on the large end face and collar of the roller, the lubricating oil film of the lubricating grease tends to break. . When the lubricating oil film breaks, metal contact occurs, causing a problem that heat generation and frictional wear increase.
For this reason, it is necessary to improve lubricity and load resistance under high speed and high load, and to prevent metal contact due to breakage of the lubricating oil film. The extreme pressure agent-containing grease is used to reduce the problems.

Conventionally, as an example of a wheel support device that is subjected to a high load at a high speed, an organometallic compound containing a metal selected from nickel, tellurium, selenium, copper, and iron is included in an amount of 20% by weight or less based on the total amount of grease A railway vehicle bearing in which grease is sealed is known (see Patent Document 1).
However, as the use conditions of the roller bearing become severe, such as lubrication under a high speed condition with a dN value of 100,000 or more, there is a problem that it becomes difficult to use the roller bearing with the conventional grease.
In the roller bearing for a wheel support device, rolling friction is generated between the rolling surfaces of the inner and outer rings and “rollers” as rolling elements, and sliding friction is generated between the collar portion and “rollers”. Since sliding friction is larger than rolling friction, seizure of the brim portion tends to occur when the use conditions become severe. For this reason, there is a problem that maintenance work-free cannot be achieved due to frequent grease replacement work.
JP-A-10-17884 (Claims)

  An object of the present invention is to provide a wheel support device that prevents frictional wear on a lubricated surface in a state where a high load or a sliding motion occurs, and is excellent in long-term durability.

Wheel supporting apparatus of the present invention is a wheel support device for rotatably supporting a rotary member which rotates together with a wheel by grease rolling bearing mounted on an outer diameter surface of the axle, the grease sealed in the grease rolling bearing A base oil, a thickener, and inorganic bismuth, wherein the thickener is at least one thickener selected from metal soap thickeners and urea compounds; kinematic viscosity at ℃ is the 33 ~ 100 mm ² / s, the inorganic bismuth is at least one selected from bismuth sulfate and bismuth trioxide, are blended 0.01-15 wt% with respect to total the grease It is characterized by being.
The base oil is characterized by comprising at least one oil selected from poly-α-olefin (hereinafter abbreviated as PAO) oil and mineral oil.
The thickener is a urea compound.
In the wheel support device of the present invention, the grease-filled rolling bearing has a thrust sliding surface.

  The bearing used in the wheel support device of the present invention encloses grease using inorganic bismuth, so that the extreme pressure effect can be maintained for a long time by replenishing inorganic bismuth to the sliding interface. Therefore, it can be suitably used for a wheel support device that requires long-term durability as well as wear resistance.

  As a result of studies to improve lubricity and load resistance under high speed and high load by using bearings filled with grease containing extreme pressure agent, inorganic bismuth was added as an additive to the entire grease. Rolling bearings filled with 15% by weight of grease have less wear under high loads and sliding movements and improve long-term durability compared to rolling bearings filled with grease containing additives other than inorganic bismuth. I understood. This is presumably because inorganic bismuth has better heat resistance and durability than materials other than inorganic bismuth, and is difficult to thermally decompose, so that the extreme pressure effect can be sustained for a long time. The present invention is based on such knowledge.

The wheel support device of the present invention will be described with reference to FIG. FIG. 1 is a cross-sectional view of a wheel support device. As shown in FIG. 1, the steering knuckle 1 is provided with a flange 2 and an axle 3. A pair of tapered roller bearings 4 a and 4 b attached on the outer diameter surface of the axle 3 constitutes an axle hub 5 as a rotating member. It is supported rotatably.
The axle hub 5 has a flange 6 on the outer diameter surface, and a stud bolt 7 provided on the flange 6 and a nut 8 engaged with the stud bolt 7 by a screw 8 and a brake drum 9 of a brake device and a wheel disc 10 of a wheel. Is installed. Reference numeral 11 denotes a rim attached to the outer diameter surface of the wheel disk 10, and a tire is attached on the rim.

A back plate 12 of a brake device is attached to the flange 2 of the steering knuckle 1 by tightening bolts and nuts. The back plate 12 supports a braking mechanism that applies a braking force to the brake drum 9, but is omitted in the drawing.
The pair of tapered roller bearings 4 a and 4 b that rotatably support the axle hub 5 are lubricated by grease filled in the axle hub 5. A grease cap 17 is attached to the outer end face of the axle hub 5 so as to cover the tapered roller bearing 4b in order to prevent grease from leaking to the outside from the tapered roller bearing 4b and intrusion of muddy water from the outside.

  An example of the tapered roller bearing of the wheel support device of the present invention will be described with reference to FIG. FIG. 2 is a partially cutaway perspective view of a tapered roller bearing. In the tapered roller bearing 4, a tapered roller 16 is disposed between an inner ring 14 and an outer ring 13 via a cage 15. The tapered roller 16 receives rolling friction between the rolling surface 14a of the inner ring 14 and the rolling surface 13a of the outer ring 13, and receives sliding friction between the flange portions 14b and 14c of the inner ring 14. In order to reduce these frictions, roller bearing grease is enclosed.

  Examples of inorganic bismuth that can be used in the grease sealed in the wheel support device of the present invention include bismuth powder, bismuth carbonate, bismuth chloride, bismuth nitrate and hydrates thereof, bismuth sulfate, bismuth fluoride, bismuth bromide, iodine Bismuth iodide, bismuth oxyfluoride, bismuth oxychloride, bismuth oxybromide, bismuth oxyiodide, bismuth oxide and its hydrate, bismuth hydroxide, bismuth selenide, bismuth telluride, bismuth phosphate, bismuth oxyperchlorate, Examples include bismuth oxysulfate, sodium bismuth, bismuth titanate, bismuth zirconate, and bismuth molybdate. High bismuth sulfate, bismuth trioxide and bisma It is a powder.

  Bismuth is a silver-white metal with the lowest thermal conductivity of all metals except mercury, a specific gravity of 9.8, and a melting point of 271.3 ° C. Bismuth powder is a relatively soft metal and tends to form a film when subjected to extreme pressure. Therefore, the particle size of the powder may be any particle size that can be dispersed in the grease. The bismuth powder used for the grease sealed in the wheel support device of the present invention is preferably 5 to 500 μm.

It is essential to add inorganic bismuth as an extreme pressure agent to the grease sealed in the wheel support device of the present invention. One kind or two kinds of inorganic bismuth may be mixed and added to the grease.
The amount of inorganic bismuth added is 0.01 to 15% by weight based on the entire grease. Preferably, it is 1 to 10% by weight. If the amount added is less than 0.01% by weight, the effect of improving the wear resistance will not be exhibited. If the amount added exceeds 15% by weight, the torque during rotation increases, heat generation increases, and rotation trouble occurs. .

  Examples of the base oil that can be used for the grease sealed in the wheel support device of the present invention include mineral oil, PAO oil, ester oil, phenyl ether oil, fluorine oil, and synthetic hydrocarbon oil (GTL) synthesized by Fischer-Tropsch reaction. Base oil). Among these, it is preferable to use at least one selected from PAO oil and mineral oil. The PAO oil is usually an α-olefin or an isomerized α-olefin oligomer or polymer mixture. Specific examples of the α-olefin include 1-octene, 1-nonene, 1-decene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1 -Nonadecene, 1-eicocene, 1-docosene, 1-tetracocene and the like can be mentioned, and usually a mixture thereof is used. Moreover, as mineral oil, what is normally used in the field | areas of normal lubricating oil and grease, such as a paraffinic mineral oil and a naphthenic mineral oil, can be used, for example.

The base oil that can be used for the grease enclosed in the wheel support device of the present invention preferably has a kinematic viscosity at 40 ° C. of 30 to 200 mm ² / s. If it is less than 30 mm ² / s, the amount of evaporation increases and the heat resistance decreases, which is not preferable. On the other hand, if it exceeds 200 mm ² / s, the temperature rise of the bearing increases due to an increase in rotational torque, which is not preferable. .

（式（１）中のＲ₂ は、炭素数６〜１５の芳香族炭化水素基を、Ｒ₁およびＲ₃ は、炭素数６〜１２の芳香族炭化水素基または炭素数６〜２０の脂環族炭化水素基または炭素数６〜２０の脂肪族炭化水素基をそれぞれ示し、Ｒ₁およびＲ₃ は、同一であっても異なっていてもよい。）
式（１）で表されるウレア系化合物は、例えば、ジイソシアネートとモノアミンの反応で得られる。ジイソシアネートとしては、フェニレンジイソシアネート、ジフェニルジイソシアネート、ジフェニルメタンジイソシアネート、１，５−ナフチレンジイソシアネート、２，４−トリレンジイソシアネート、３，３−ジメチル−４，４−ビフェニレンジイソシアネート、オクタデカンジイソシアネート、デカンジイソシアネート、ヘキサンジイソシアネー卜等が挙げられ、モノアミンとしては、オクチルアミン、ドデシルアミン、ヘキサデシルアミン、ステアリルアミン、オレイルアミン、アニリン、ｐ−トルイジン、シクロヘキシルアミン等が挙げられる。
ウレア化合物は、イソシアネート化合物とアミン化合物を反応させることにより得られる。反応性のある遊離基を残さないため、イソシアネート化合物のイソシアネート基とアミン化合物のアミノ基とは略当量となるように配合することが好ましい。
基油にウレア化合物を配合して各種配合剤を配合するためのベースグリースが得られる。ベースグリースは、基油中でイソシアネート化合物とアミン化合物とを反応させて作製する。 Thickeners that can be used in the grease sealed in the wheel support device of the present invention include metal soap thickeners such as aluminum, lithium, sodium, composite lithium, composite calcium, composite aluminum, and diurea compounds of the following formula (1) Is mentioned. Preferably, it is a diurea compound. These thickeners may be used alone or in combination of two or more.

(R ₂ in the formula (1) is an aromatic hydrocarbon group having 6 to 15 carbon atoms, R ₁ and R ₃ are an aromatic hydrocarbon group having 6 to 12 carbon atoms or an oil having 6 to 20 carbon atoms. Each represents a cyclic hydrocarbon group or an aliphatic hydrocarbon group having 6 to 20 carbon atoms, and R ₁ and R ₃ may be the same or different.)
The urea compound represented by the formula (1) is obtained, for example, by reaction of diisocyanate and monoamine. Diisocyanates include phenylene diisocyanate, diphenyl diisocyanate, diphenylmethane diisocyanate, 1,5-naphthylene diisocyanate, 2,4-tolylene diisocyanate, 3,3-dimethyl-4,4-biphenylene diisocyanate, octadecane diisocyanate, decane diisocyanate, hexane diisocyanate. Examples of the monoamine include octylamine, dodecylamine, hexadecylamine, stearylamine, oleylamine, aniline, p-toluidine, cyclohexylamine and the like.
A urea compound is obtained by reacting an isocyanate compound and an amine compound. In order not to leave a reactive free radical, the isocyanate group of the isocyanate compound and the amino group of the amine compound are preferably blended so as to be approximately equivalent.
Base grease for blending various compounding agents by blending a urea compound with a base oil can be obtained. The base grease is produced by reacting an isocyanate compound and an amine compound in a base oil.

  The grease to be sealed in the wheel support device of the present invention can contain a known additive in the grease as necessary. Examples of the additives include organic zinc compounds, amine-based, phenol-based, sulfur-based antioxidants, metal deactivators such as benzotriazole and sodium nitrite, and viscosity index improvers such as polymethacrylate and polystyrene. Examples thereof include solid lubricants such as molybdenum sulfide and graphite. These can be added alone or in combination of two or more.

  The grease that can be used in the wheel support device of the present invention can also be used in bearings that are subjected to high loads other than the wheel support device.

Examples 1 to 8
In a reaction vessel, add a thickener to the base oil, homogenize it using a three-roll mill, and mix with Li soap / mineral oil grease (40 ° C base oil viscosity 100 mm ² / s, shown in Table 1). Consistency 220), urea / PAO grease (40 ° C base oil viscosity 46 mm ² / s, miscibility 280), Li soap / ester oil grease (40 ° C base oil viscosity 33 mm ² / s, miscibility) 250) and urea / ether grease (40 ° C. base oil viscosity 100 mm ² / s, blending degree 300). Further, inorganic bismuth as an extreme pressure agent was added to the above greases in the proportions shown in Table 1 to prepare greases of respective examples. The obtained grease was subjected to the following extreme pressure evaluation test and roller bearing test. The results are also shown in Table 1.

Comparative Example 1 to Comparative Example 9
In a reaction vessel, add a thickener to the base oil, homogenize using a three-roll mill, and mix with Li soap / mineral oil grease (40 ° C base oil viscosity 100 mm ² / s, mixed in Table 2). Consistency 220), urea / PAO grease (40 ° C base oil viscosity 46 mm ² / s, miscibility 280), Li soap / ester oil grease (40 ° C base oil viscosity 30 mm ² / s, consistency) 250) and urea / ether grease (40 ° C. base oil viscosity 100 mm ² / s, blending degree 300). Further, organic bismuth, MoDTC, and the like as extreme pressure agents were added to the above greases in the proportions shown in Table 2 to prepare greases for each comparative example. The obtained grease was subjected to an extreme pressure evaluation test and a roller bearing test in the same manner as in the example. The results are shown in Table 2.

Extreme pressure evaluation test:
An extreme pressure evaluation test apparatus is shown in FIG. The evaluation test apparatus is composed of a φ40 × 10 ring-shaped test piece 19 fixed to the rotating shaft 18 and a ring-shaped test piece 20 in which the end faces 21 and the end faces 21 are rubbed together. Grease for roller bearings was applied to the end face 21 portion, and the extreme pressure property was evaluated by applying an axial load of 490 N and a radial load of 392 N in the right direction A in FIG. The extreme pressure property was measured by measuring the vibration of the rotating shaft 18 caused by an increase in frictional wear at the sliding portions of both test pieces with a vibration sensor, performing the test until the vibration value was twice the initial value, and measuring the time.
The longer the time it takes for the vibration value of the rotary shaft 18 to be twice the initial value, the greater the extreme pressure effect, and the better the heat resistance and durability. Therefore, the heat resistance durability of the grease was evaluated by comparing each example with each comparative example for the measured length of time.
Roller bearing test:
3.620 g of grease was sealed in a 30206 tapered roller bearing, the bearing was operated at an axial load of 980 N, a rotational speed of 2600 rpm, and room temperature, and the surface temperature of the collar part during rotation was measured. After the start of operation, the average value of the collar surface temperature for 4 to 8 hours was calculated.
When the sliding friction generated between the collar portion and the “roller” increases, the surface temperature of the rotating collar portion increases. Therefore, the heat resistance durability of the grease was evaluated by comparing each example with each comparative example at the measured temperature. The above-mentioned temperature height was less than 70 ° C., which was the standard for the heat resistance and durability of grease.

In Tables 1 and 2, the data of Li soap / mineral oil grease is compared between each example and each comparative example. In the type of extreme pressure agent, inorganic bismuth is more than organic bismuth. The test showed excellent heat durability.
In Example 2 and Comparative Example 5, it can be seen that bismuth trioxide exhibits a heat durability of about 3 times that of organic bismuth. From these facts, inorganic bismuth is superior to organic bismuth in heat resistance and resistance to thermal decomposition, so it is considered that the extreme pressure effect can be maintained for a long time.
Among bismuth sulfate, bismuth trioxide and bismuth powder, bismuth powder showed the best heat resistance and durability.

  As shown in Example 2, Example 5 and Example 6, the extreme pressure effect tends to increase as the amount of bismuth trioxide added increases to 1, 5 and 15% by weight. Even if the amount is increased to 3 times the 15% by weight and 5% by weight added, the increase in extreme pressure effect is only about 1.4 times. This is probably because when the amount of bismuth trioxide added approaches 15% by weight, the torque during rotation increases, heat generation increases, and rotation failure tends to occur.

  In Tables 1 and 2, the data of urea / PAO grease, Li soap / ester oil grease, and urea / ether grease are compared with each of the examples and comparative examples. In the type of pressure agent, inorganic bismuth such as bismuth sulfate and bismuth trioxide exhibits superior heat resistance and durability than organic bismuth. As shown in Example 3, Example 4 and Comparative Example 7, bismuth sulfate has a heat resistance of about 3 times that of organic bismuth, and bismuth trioxide has a heat resistance of about 4 times that of organic bismuth. It turns out that it shows durability. This is presumably because inorganic bismuth is superior to organic bismuth in heat resistance and resistance to thermal decomposition, so that the extreme pressure effect can be maintained for a long time.

Further, as shown in Example 7 and Comparative Example 3, in the case of Li soap / ester oil based grease, heat resistance and durability is about 13 times higher when bismuth sulfate is used as an extreme pressure agent than when no extreme pressure agent is used. Showed sex.
In addition, as shown in Example 8 and Comparative Example 4, in the case of urea / ether grease, when bismuth trioxide is used as an extreme pressure agent, the heat durability is about 6 times that when no extreme pressure agent is used. showed that. From the above, it can be seen that inorganic bismuth such as bismuth sulfate and bismuth trioxide maintains the extreme pressure effect for a long time.

  Since the wheel support device of the present invention encloses grease using inorganic bismuth excellent in heat resistance and durability, the extreme pressure effect can be maintained for a long period of time. Therefore, it can be suitably used for railway vehicles, construction machines, automobile electrical accessories and the like that are required to have long-term durability in addition to wear resistance.

It is sectional drawing of a wheel support apparatus. It is a partially cutaway perspective view of a tapered roller bearing. It is a figure which shows an extreme pressure property evaluation test apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steering knuckle 2 Flange 3 Axle 4 Tapered roller bearing 5 Axle hub 13 Outer ring 14 Inner ring 15 Cage 16 Tapered roller 18 Rotating shaft 19, 20 Ring-shaped test piece 21 End face

Claims (5)

In the wheel supporting device for rotatably supporting a rotary member which rotates together with a wheel by grease rolling bearing mounted on an outer diameter surface of the axle, grease sealed in the grease rolling bearing and base oil, a thickener , Including inorganic bismuth,
The thickener is at least one thickener selected from metal soap thickeners and urea compounds,
The base oil has a kinematic viscosity at 40 ° C. of 33 to 100 mm ² / s,
The wheel support device according to claim 1 , wherein the inorganic bismuth is at least one selected from bismuth sulfate and bismuth trioxide, and is blended in an amount of 0.01 to 15% by weight based on the whole grease.   The wheel support device according to claim 1, wherein the inorganic bismuth is bismuth sulfate.   The wheel support device according to claim 1 or 2, wherein the base oil is made of at least one oil selected from poly-α-olefin oil and mineral oil.   The wheel support device according to any one of claims 1 to 3, wherein the thickener is a urea compound.   The wheel support device according to any one of claims 1 to 4, wherein the grease-filled rolling bearing has a thrust sliding surface.

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